1. Field of the Invention
The present invention relates to a lighting apparatus.
2. Description of the Related Art
At present, a fiber light source in which a small-size solid light source and an optical fiber are combined has been developed. This fiber light source is used as a lighting apparatus which irradiates light from a front end of a fine structure.
As an example of such lighting apparatus, a fiber light source apparatus (light outputting apparatus) in which a solid light source is used has been proposed in Japanese Patent Application Laid-open Publication No. 2009-3228 (FIG. 17A, FIG. 17B, and FIG. 17C). FIG. 17A is a diagram showing a schematic structure of an area around a wavelength converting member of the conventional lighting apparatus, FIG. 17B is a front view showing a structure of a spacer used in the lighting apparatus of FIG. 17A, and FIG. 17C is a diagrammatic perspective view showing a structure of the spacer used in the lighting apparatus of FIG. 17A.
In the fiber light source apparatus disclosed in Japanese Patent Application Laid-open Publication No. 2009-3228, a light guiding member (an optical fiber) 920 is connected to a small size solid light source, and a wavelength converting member (a fluorescent substance) 940 is installed at a front end of the light guiding member 920. The light guiding member 920 is installed on a holding member 930, and a spacer 950 is installed between the light guiding member 920 and the wavelength converting member 940. The spacer 950 has a through hole 950c, and a metallic thin film 950a is formed on a surface of the spacer 950. In this fiber light source apparatus, by making light launched rearward which has launched from the wavelength converting member 940 toward the light guiding member 920, reflect by a reflecting portion made of the metallic thin film 950a provided on the surface of the spacer 950 the light launched toward the light guiding member 920 is returned to the wavelength converting member 940, thereby increasing an amount of light illuminated which is subjected to wavelength conversion.
The fiber light source apparatus in Japanese Patent Application Laid-open Publication No. 2009-3228 which includes a light outputting element, a guiding member which guides light from the light outputting element, a holding member which is installed on at least an emerging-side end portion of the light guiding member, and a wavelength converting member which is provided on an emerging side of the light guiding member, and which absorbs at least a part of the light from the light outputting element, and converts to a light of different wavelength. In this structure, a spacer which reflects light launched rearward from the wavelength converting member is installed between the holding member or the light guiding member, and the wavelength converting member. According to such structure, since it is possible to reduce a loss of light generated by the light reflected at or generated from the wavelength converting member being incident on an end surface of the holding member, it is possible to improve an output of light. Consequently, by providing a means which reflects the light in a direction in which the light is to be output, it is possible to improve brightness of light launched rearward which could hitherto not be used effectively.
However, in the abovementioned fiber light source apparatus, an arrangement is made such that an entire surface of an opening on an emerging side of the spacer 950 is covered by the wavelength converting member 940. Therefore, the light launched rearward which is reflected at a reflecting portion made of the metallic thin film 950 formed on the surface of the spacer 950 passes through the wavelength converting member 940 and is output to outside. However, since the wavelength converting member 940 has a self-absorbing property, the wavelength converting member 940 absorbs a part of the light subjected to wavelength conversion by the wavelength converting member 940, and accordingly, an amount of the wavelength-converted light which is launched to outside is reduced. Consequently, in the structure of the abovementioned fiber light source apparatus, the wavelength-converted light from the wavelength converting member 940 cannot be used sufficiently, and light extraction efficiency is not improved as it has been expected to be.